Identification of distinct swallowing patterns for different bolus volumes

Abstract Objective To investigate the time interval between glottic closure and the opening of upper esophageal sphincter during swallowing, by means of the coupling of electromyographical (EMG) recordings on the thyroarytenoid (TA) and the cricopharyngeus (CP) muscles. Methods TA-EMG and CP-EMG pause were recorded by concentric needle electrodes using time-locked delay-line circuitry of the EMG apparatus. EMG data obtained from a total of 273 swallows of saliva, 3, 5, 10 and 15ml volumes of water, were compared. Results The relation between the onsets of TA-EMG activity and the CP-EMG pause demonstrated three different patterns of swallows. Pattern A was the delay of the onset of TA-EMG between 50–500ms, and pattern B was the overlap of its activity with the CP-EMG pause. Pattern C was the earlier occurrence of the TA-EMG 50-550ms before the CP-EMG pause. Pattern A was the most frequent type of swallows whereas the pattern C appeared during swallowing of larger volumes. Conclusions Physiologically, there is a delay of the TA activation after the onset of CP-EMG pause during swallowing of small amounts in healthy subjects. Significance This physiological phenomenon could be a potential risk of aspiration in patients with neurogenic dysphagia.